Questions tagged [fluorescence]
For questions relating to the radiation emitted by substances as a result of incident radiation.
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Fluorescence Intensity and Fluorescence Quantum Yield
I plan to use ImageJ to analyze some fluorescence experiments where the pH changes. I will be using fluorescein as the indicator for the pH changes and it will be present in low concentration (like is ...
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How ph affects aesculune fluorescence?
I am facing a ween problem. I am trying to find out, how would look like the graph for fluroscence of aesculine (intensity of fluoroscence on Y axis and pH on X axis).
I know, that increasing the pH ...
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Microcopy Fluorescence filter set usefulness
I have a brief doubt and maybe someone around here can give as some help. We are doing a pilot study on microplastics using a fluorescence method (red nile). The dye is solvachromic, so it's emission ...
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Fluorescence quenching by palladium(II) vs. platinum(II) complexes
Why do we observe much stronger (in most cases complete) fluorescence quenching by $\ce{Pd^2+}$ than $\ce{Pt^2+}?$ I work with complexes of both metals and there is no real 100% explanation I can find ...
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Why is there a mirror image effect in the absorbance and fluorescence spectra?
I've read some answers online but I still can't seem to understand the mirror image effect. Why is the highest energy absorption (v" = 0 to v' = 4) the lowest energy fluorescence (v' = 4 to v&...
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Which commonly available UV light source to use with fluorescein
I want to start experimenting with fluorescein. I have a 353 nm UV light source, but am thinking that it might be too short since it looks like peak excitation occurs at 494 nm. So am I correct in ...
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Why do different substances containing saturated hydrocarbons burns with different flame?
LPG and Candle wax both contain saturated hydrocarbon, yet LPG gives a clean white flame but a candle gives yellow flame with lots of smoke. Why so?
I have read some answers on web which says that it ...
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Help with Forster distance conversion for FRET
For my project on Fluorescence, I'm trying to simplify the equation for the Forster distance (I obtained this from the Lakowicz book). To keep track, the units are in square brackets.
$$R_0 = \left(\...
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Why does the emission of dansyl group diminish with time in this experiment?
I don't know how to make sense of this. I what is happening when an enzyme (carboxypeptidase, which contains tryptophan as its only chromophore and uses a Zn(II) ion in its active center) hydrolises a ...
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Fluorometer for measuring fluorescence in a sheet of water
Does anyone know of a fluorometer that I could use to measure fluorescence in a thin sheet of water. So it would be like holding a piece of writing or printer paper vertically and trying to get a ...
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Implications of the excitation spectra
The fluorescence excitation spectra show the change in fluorescence intensity as a function of the wavelength of the excitation light.
I'm interested in the certain physical implications of the above.
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Absorption and emission at same wavelength?
Is it possible for a molecule to absorb and emit at the same wavelength? What is the reason behind it?
I’m working on charged tin porphyrins and got the excitation and emission (fluorescence) ...
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Data analysis in TCSPC for fluorescene decay (reconvolution with measured IRF)
I am trying to understand the data analysis of fluorescence decay counts measured by TCSPC technique, particularly with reconvolution with measured IRF.
I am able to get the fitted counts (given by ...
- 139
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Chemical Potential in the Fluorescent Molecule
I'm reading this paper, which states that the chemical potential $\mu$ is determined by the steady-state balance of up and down transitions in a fluorescent molecule. I am happy with this ...
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Common chemcials that produce phosphorescence
Are there any common lab chemicals or household stuff that produce phosphorescence?
I am aware of ZnS, CaS, Fluorescein, Erythrosin B, Vanillin Benzaldehyde, Vitamin B2, Tryptophan etc.
I just need ...
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Is the XRF spectroscopy equally sensitive for every element?
I am curious whether or not every element can be equally well detected by using X-Ray-fluorescence-spectroscopy. Might there be any contitions or circumstances that make it hard/impossible to detect a ...
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Why do some molecules show non-symmetric absorption and emission bands?
I'm looking at a molecule of [Ru(bpy)3]2+ in water and the absorption and emission bands are not symmetrical. I want to know why the mirror image rule doesn't apply here. Is this because of the MLCT, ...
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Nitrogen dioxide fluorescence quenching and lifetime
Nitrogen dioxide fluorescence quenching:
$$
\begin{align}
\ce{NO2 + h\nu &->[$\varphi_\mathrm{Ia}$] NO2^{\ast}}\tag{I}\\
\ce{NO2^{\ast} &->[$k_2$] NO2 + h\nu'}\tag{II}\\
\ce{NO2^{\ast} +...
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Are there any fluorophores with lifetimes in the micro to milli second range?
I'm looking for a fluorophore with exceptionally long lifetime to use in an oxygen optode (the longer the lifetime the less timing precision needed in the electronics).
So far the longest I have ...
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Deriving fluorescence intensity equations
I've been having trouble with deriving the equations in the following problem.
The interaction between DNA and AO to form the AO–DNA complex can be expressed by the following reaction:
$$\ce{...
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Latent blood detection with fluorescein
I need help with the reaction between fluorescein and blood in the method of detecting latent blood stains.
I find it hard to find any literature on this subject.
As far as I am concerned, the ...
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When an electron is excited to a singlet state, must it flip its spin state to enter the triplet state and flip once more to the ground state?
I understand the Jablonski diagram in that it has intersystem crossing from the singlet state to the triplet state, but how many spin switches are necessary to complete to phosphores? When an electron ...
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Is the activation energy always inversely proportional to the reaction rate?
When I obtained the activation energy using the Arrhenius equation for a 10-minute glowstick (rapid, rigorous reaction), it was almost 4 times that of a 12-hour glowstick (slow, mild reaction).
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Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf? [closed]
I'm stumped by this question:
Why has nature evolved to put a porphyrin (i.e. chlorophyll) as the chromophore in a leaf?
I've thought that it might have something to do with how sun emits light ...
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How to calculate molecular emission spectra?
Is there free software that can calculate the fluorescence emission spectra of organic molecules?
Let's say, for example, rubrene
There is a bunch of quantum free quantum chemistry software:
https://...
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Does something like a fluorescent foil or a fluorescent film exist?
During my experiments I want the emitted laser beams to come back with a different wavelength than the original wavelength using a fluorescent foil or fluorescent film.
The laser I'm currently using ...
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Why are glow-in-the-dark things usually green?
I've noticed that many glow-in-the-dark objects you can purchase in the store are green. Occasionally I would come across something that was orange or blue, but mostly it seems that green is the ...
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Why do glow-in-the-dark substances dim gradually?
Related: How do things glow in the dark?
Growing up, I had glow-in-the-dark stars on my ceiling and after being "charged" by having my lights on, they would phosphoresce for quite some time.
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Measuring a high Michaelis constant using fluorescence
We have the task of measuring kinetic parameters of an oxidase reaction that has a $K_M$ of about $2 \,\text{mM}$. For that, we want to use a fluorescence assay based on Amplex Red. The latter is a ...
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Choosing the right wavelength for calibration curve and for analysis of actual results
Introduction:
I am currently conducting a series of experiments in which I am studying the transport of polystyrene nanoparticles (PNPs) through sand and soil. This is done in sand/soil columns, into ...
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